1. Field
The disclosed embodiments relate generally to IP telephony.
2. Background
Mobile communication devices such as cellular telephones may have more than one air interface. In one example, a cellular telephone is able to communicate conventionally over relatively long distances with a cellular telephone network using a CDMA (Code Division Multiple Access) transceiver. The CDMA transceiver of the cellular telephone communicates with a cellular BTS (Base Transmitter Site) on the cellular telephone network. In addition, the cellular telephone is able to communicate over relatively short distances with a wireless local area network (LAN) using an IEEE 802.11 transceiver. The IEEE 802.11 transceiver of the cellular telephone communicates wirelessly with an access point on the LAN.
A first party may use the cellular telephone to place call to a second party using VoIP (voice over Internet Protocol) technology. Voice data is communicated in IP packets from the cellular telephone, over the 802.11 wireless link to the access point, through the LAN, and across the Internet to the second party. When the first party is engaged in such a call, the first party may move the mobile communication device with two air interfaces and end up with two active interfaces with less than perfect coverage. The conventional approach is to start using the interface with better coverage and start sending Real Time Traffic like RTP using the better interface. Because the mobile communication device does not have perfect coverage on the interface switched to, the quality of service may be affected. The chosen interface is then used to sent RTP data until coverage on that interface is completely lost or until coverage on the other interface improves. A solution is desired.